The present disclosure relates to a power amplifier module.
In mobile communication devices, such as cellular phones, a power amplifier module for amplifying power of a signal to be transmitted to a base station is used. Nowadays, in cellular phones, modulation methods using standards for high-speed data communication, such as HSUPA (High-Speed Uplink Packet Access), LTE (Long Term Evolution), and LTE-Advanced, are being used. In these communication standards, for enhancing the communication speed, it is desirable to decrease a phase deviation and an amplitude deviation. Accordingly, it is necessary that a power amplifier module implement high linearity. In the above-described communication standards, for achieving the enhanced communication speed, the range in which the amplitude of a signal changes (dynamic range) is usually wide. For maintaining high linearity even in the case of a wide dynamic range, a high power supply voltage is necessary, and this is likely to increase the power consumption in a power amplifier module.
On the other hand, in cellular phones, for increasing the maximum talk time or the maximum communication time, it is desirable to decrease the power consumption. For example, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2005-513943 discloses a power amplifier module utilizing the envelope tracking technique. In the envelope tracking technique, by adjusting the power supply voltage in accordance with the amplitude level of an input modulation signal, the power efficiency is improved.